Lorraine Pascale is the world's least likely cake-maker. She's 36 years old and beautiful: leggy, sleek, ineffably glam, the kind of slender that suggests daily exercise and minimal exposure to candy-coloured confection. For most of the 1990s she worked as a model. She was spotted, aged 16, fresh out of her boarding school in Devon; she was instantly successful. She lived in New York, held her own among the biggest names of the day; she was the first British black model to land the cover of American Elle. She walked runways and shot major commercial campaigns for Versace and Donna Karan, for Benetton and Gap. It was, she says: "Amazing! Incredibly glamorous! New York in the heyday with Naomi and Cindy and Linda at every show ... limousines waiting to pick you up. Mobile phones before anyone else had them ..."

And yet, today, Pascale's business is cake: cupcakes, brownies, birthday and Christmas cakes. She's a baker of repute. She has an exclusive deal with Selfridges, who stock her high-end celebration cakes and who are on the verge of introducing her quality-cupcake concept to the people of Birmingham via their fancy food hall. "The cupcake is still such a fashion, London-y idea" says Pascale. "But not for much longer." When we meet, she is a week away from signing a lease on Ella's Bakehouse, her first stand-alone cake shop. It is named after her daughter ("who has gone teen overnight and isn't interested any more") and is due to open this summer.

So, I say: given that models (tall, thin, terrifying) and cake (short, sweet, fat and fattening) should not even inhabit the same universe, how on earth did Pascale make the transition? And also - why.

"It wasn't a long-standing ambition or anything," Pascale says. She stands, impossibly chic in chef whites, in the middle of an uninspiring, highly functional kitchen space in south London. She's got a rack of brownies in front of her; an overwhelming quantity of cupcakes lurk in nearby boxes. She has to ice them by hand, and really quite soon. "Actually, I wanted to be a police officer. That was my dream when I was a child. But mostly - I wanted to do something I was passionate about. I enjoyed modelling, but I wasn't passionate about it. A few years ago I gave it up and started doing loads of different courses, trying to find the one that really made me tick."

She worked as a trainee mechanic at a Skoda garage in Deal. She did "a hundred different things, and gave up halfway through. And then [in 2005] I enrolled on a course at Leith's." Halfway through day one of Leith's demanding full-time diploma in food and wine, Pascale realised she'd found her thing. "I fell in love with it. The first day.

I thought: I've arrived. I imagined it would be women sitting around doing Victoria sponges. I didn't realise it was going to be tantrums, tiaras, arguments, people storming out, people quitting ... It was tough. Hard.

A full year of very long days. Lots of theory. Loads of exams. We had a test once a week, an exam once a month, and then a huge exam at the end... But it was like putting on the right clothes or shoes or something. It just - fit."

Pascale graduated from Leith's and began working in various restaurants. "I did stages at the Mandarin Oriental, at Tom Aitkens. I went to Gilgamesh in Camden and Pengelley's with Ian Pengelley." But working 18-hour days while attempting to care for her daughter Ella (who is now 12) was unrealistic; plus, Pascale says: "I left home at 16 and I've been self-employed ever since. Working for other people... Oh, I'm not very good at being told what to do, let's put it like that." After a year of intense slog in London's challenging kitchens, she answered an advert on website gumtree.com and got a job at London cake destination the Hummingbird Bakery. Eight months into that she decided to start her own cake business. "Gluten-free at first. Because every woman thinks they've got a problem with wheat." She laughs. "Only of course - we haven't." She quickly abandoned the gluten-free endeavour and focused instead on home baking. "I like to cook savoury too - but I don't love it in the same way. There's something so comforting about cakes. The smell, the making of it. The eating. Everyone always goes: 'Wow!' when you bring a cake to the table. Everyone says: 'Oh - just a little bit then! Just a little bit!'" At first Pascale made and sold birthday cakes to the parents of Ella's schoolfriends; then Marco Pierre White - who Pascale knew from her modelling career - suggested that she speak to Selfridges' food director Ewan Venters. In 2008 Venters commissioned her to work on a range of celebration cakes, and Pascale's business truly took shape. "Doing the Christmas cakes was the big break. Just incredible. Two hundred and fifty of them, and I did them all myself. Seeing them on the shelves was an amazing feeling."

Lorraine Pascale is hard-working ("I still do 18 hours a day. I don't need more than four hours' sleep") and ambitious. She's planning on a programme of "rapid expansion. I want Ella Bakehouse shops all over the country." Cakes are, she reckons, recession-proof. "After the initial January of doom: 'Everyone's going to die, let's just eat potatoes' ... After that part - which was awful, wasn't it? - people started to feel better, and home baking started to boom. The Mintel reports show it. The trade magazines talk about it. And you can feel it, can't you? Yes. This is definitely a very good time for cakes."

• Lorraine Pascale cakes are available from Selfridges. She is represented by Storm Models.